History of Air-Analysis 



31 



wise the nitrogen. By using large glass vessels which could be evacuated 

 and passing the air over heated metallic copper, they absorbed the oxy- 

 gen by the copper, weighing the vessel before and after absorption, thus 

 giving a true weight of the nitrogen left behind. The method was ob- 

 viously best used by its illustrious devisers, since it was much more tech- 

 nical and difficult to carry out than any previously suggested. By means 

 of two apparatus, simultaneous experiments were made in 1841. The 

 percentage volumes of oxygen found are given in table 8. These samples 

 were all taken during very clear and beautiful weather, and as a control 

 a sample was taken on May 29, 1841, during rain. The result was essen- 

 tially that found during the clear weather, viz, 20.817 per cent of oxygen. 



Table 8. Percentages of oxygen in air analyzed by Du mas and Boussingault. 



Although the experimental evidence of Gay-Lussac and von Hum- 

 boldt, as well as the earlier observations of Boussingault in South America, 

 agreed perfectly with the more recent work of Dumas and Boussingault, 

 nevertheless, owing to the importance of the Dalton hypothesis, Dumas 

 and Boussingault decided upon making some analyses of air taken from 

 the Faulhorn. By previous arrangement with Brunner in Berne, a series 

 of experiments was planned in which samples of air would be taken simul- 

 taneously in Paris, Berne, and on the Faulhorn. These latter were col- 

 lected by means of large evacuated glass balloons which were sent by 

 Dumas from Paris. In Berne, Brunner operated with his method pre- 

 viously described. The results of these comparisons, which represent the 

 first cooperative investigation of any magnitude on the composition of 

 the air, are given in table 9. 



Table 9. Percentages of oxygen in air analyzed by Dumas and 

 Boussingault, and by Brunner. 



While there is a difference between the samples in Paris and the sam- 

 ples in Berne and on the Faulhorn, it is important to note that somewhat 



